It's illegal to own just one guinea pig in Switzerland because they get lonely.

Here are eight fun facts about federal retirement that might not only spark a conversation in the carpool but also could help you in planning for your retirement.

The federal retirement system is almost 100 years old. The 1920 act creating it included a single mandatory retirement age of 70. No earlier retirement was permitted except for disability, although in 1922 a retroactive provision was introduced allowing discontinued service retirement at age 55 with 15 years of service. No survivor annuity benefits were payable and for service of 30 years or more, the basic annuity was 60 percent of the final 10-year average salary, with a minimum benefit of $360 per year and a maximum of $720. That wasn’t enough to live on even at that time.

Views on retirement were a bit different back then. During a 1924 congressional hearing, Ed J. Cantwell, secretary of the National Association of Letter Carriers, had this to say: “One does not stick to a job 30 years and then lightly give it up, particularly when retirement brings home the gaunt, ghostly fact that old age is close at hand and advancing with his inseparable companion, the grim reaper.”

There is currently more than $500 billion invested in the Thrift Savings Plan. It is the largest employer-sponsored savings plan, and disburses more than 200,000 monthly payments. Over 150,000 participants per year withdraw a single payment from their TSP accounts as cash or transfer it to another retirement account, amounting to over $9 billion per year leaving the TSP.

Withdrawals from traditional TSP accounts are taxed as ordinary income. Many employees have plans to pay down or pay off their mortgage by taking a post-retirement lump-sum withdrawal from their TSP account. Some think there is preferential tax treatment on these withdrawals, as there is with long-term investment gains. But traditional (as opposed to Roth) TSP withdrawals will be added to your other income and taxed at the ordinary rates on the federal level. Also, be aware of the 10 percent tax penalty on early withdrawals if you’re resigning or taking early retirement before age 55 (with the exception of law enforcement officers and other retired public safety officers). And don’t forget about state income taxes in retirement.

Older adults are working longer.As of 2014, 23 percent of men and 15 percent of women aged 65 and older were in the labor force, and these levels are projected to rise further by 2022, to 27 percent for men and 20 percent for women. According to the Census Bureau, the nation's 90-and-older population has nearly tripled over the past three decades, reaching 1.9 million in 2010. Over the next 40 years, this population is projected to more than quadruple. An older person's likelihood of living in a nursing home increases sharply with age. Federal retirees should recognize the value of lifetime pensions and health insurance, and weigh the value of lifetime survivor benefits that are adjusted for inflation.

There’s a 76 percent difference in the Social Security Benefit when claimed at age 62 vs. age 70. You can get $700 to more than $1,000 in additional benefits by delaying until you’re 70. But it only makes sense to wait if most of the following statements are true:

You are still working at age 62 and beyond.

You can live comfortably without claiming early.

You have enough investment income to withdraw larger payments in your early retirement years while delaying Social Security—and the discipline to cut back the larger payouts in your later years once you start to receive Social Security benefits.

You have an average or above average life expectancy.

You are the higher income earner of a married couple.

You are the older spouse of a married couple.

There are more than 250 health plans in the Federal Employees Health Benefits Program. But according to a 2017 Government Accountability Office report, two-thirds of all participants choose one of the two options under Blue Cross and Blue Shield Association plans. The other most popular FEHBP plans are GEHA, Kaiser Permanente, MHBP and Aetna.

Federal Employees Group Life Insurance is not always the cheapest option, but it offers important benefits. These include Basic and Option B benefits that increase as your basic pay rate does. FEGLI follows you into retirement as long as you retire with an immediate annuity and you’ve maintained the coverage for the last five years of your career.

Federal employee benefits do not include disability insurance. But sick leave and disability retirement provide for times when federal employees can’t work due to illness or disability. Employees earn 104 hours of sick leave per year. Those covered under the Federal Employees Retirement System are eligible to apply for disability retirement after completing 18 months of service if they are diagnosed with a condition that prevents them from doing their job for at least a year.